Stories similar to Graphical Mode Login

I am now using ubuntu12.04 with kernel version 3.5.0-42.
I got kernel 3.5.1 from kernel.org and build my own modules and kernel just in order to run my own kernel. After i did the job it booted OK, but network no longer available. With command 'ifconfig eth0' it printed err infor 'eth0 device not found'.

When a user process runs a portion of the kernel code via a system call, the process temporarily becomes a kernel process and is in kernel mode. While in kernel mode, the process will have root (i.e., administrative) privileges and access to key system resources.